1. Field of the Invention
This invention relates to a printer control device, and more particularly to an improvement of a printer control device.
2. Discussion of the Related Art
Typically, printers have an automatic sheet supplying tray or cassette for supplying recording sheets. The recording sheets are automatically supplied from the automatic sheet supplying tray or cassette to the recording section of the printer, where characters and pictures are printed on them. In this connection, a variety of recording systems are available.
In general, recording sheets are supplied to the sheet supplying tray by an operator who visually detects the number of recording sheets remaining in the tray, and replenishes the tray with recording sheets, when necessary. In one example of a printer, when the number of recording sheets in the tray reaches a predetermined value, a lamp or buzzer is operated to inform the operator that the number of recording sheets remaining in the tray is less than the predetermined value.
The above-described conventional methods of detecting the number of recording sheets in the tray suffers from the following difficulties:
The conventional methods can be used to detect that the number of remaining recording sheets is less than a predetermined value, and transmit a signal that it is necessary to replenish the tray with recording sheets. However, these methods cannot be used to accurately detect how many sheets can be used for printing at that time instant. Accordingly, when a large number of documents are being copied, the printer is sometimes forced to suspend the printing operation when it runs short of recording sheets.
Recently, data processing systems have been extensively employed in which a plurality of data processing units such as computers and workstations are connected to one printer, so that information is printed out according to the file data provided by these data processing units. The file data to be printed out, is transmitted from the data processing units, and stored in the request file storing means in the printer. The file data thus stored is successively transferred to the recording section in the printer, where it is printed out.
As is apparent from the above description, although the quantity of data to be printed at one time is being increased, it is impossible for a printer using the conventional methods to accurately detect the quantity of data stored in the request file storage and the number of recording sheets remaining in the tray or cassette. Therefore, a printer using the conventional methods cannot determine whether the printer will run short of recording sheets.
If the printer runs short of recording sheets, and the printing operation is suspended, then those users utilizing the printer are forced to wait until the printer is replenished with recording sheets. This results in a reduction of the data processing efficiency.